This invention relates to electrochemical production of alkali alcoholates, also called alkali alkoxides, and more particularly to the electrochemical production of alkali alcoholates from alkali metal salt solutions and alcohol using an electrolytic cell having an alkali ion conducting ceramic solid electrolyte and separator.
Alkali alcoholates are chemical compounds that are used in a wide variety of industrial applications. Electrolytic systems have been proposed for use in producing alkali alcoholates from salt solutions. In these systems, various ion-conducting solid electrolyte and separator material may be positioned between anolyte, buffer and catholyte compartments for transportation of ions through the alkali ion conductor from one compartment to the other. The solid electrolyte is a specific alkali ion conductor made of polymeric materials or ceramic materials or combinations of ceramic and polymeric materials.
Polymeric materials are often used as electrolytes in the electrolysis of salt solutions because of their high conductivity and resistance to acidic and caustic environments. One disadvantage of polymers, however, is their low selectivity for ionic species. They may permit the desired alkali metal ions to pass through the membrane, but they also allow the electroosmotic transport of water, the result of which is an inefficient operation of the electrolytic cell.
One particularly useful alkali alcoholate is sodium methylate, also called sodium methoxide. Sodium methoxide is made industrially in a sodium-based process in which sodium metal is reacted with methanol to produce sodium methoxide. This method uses sodium metal as a raw material. However, sodium metal is expensive and it may react violently with lower alcohols, thus rendering the process difficult to control. Sodium metal also reacts violently with water requiring elaborate and expensive equipments and systems for storage, handling, and delivery of sodium metal.
Other commercial methods may include making sodium methoxide from a sodium amalgam produced from the chlor-alkali electrolysis in a mercury cell, by reacting amalgam with alcohol. The drawback of this process is that it can result in the contamination of the product and the environment with mercury, a well known carcinogen. For this reason, use of sodium methoxide produced by this method is, in many cases, unattractive for agriculture, pharmaceuticals, and bio-diesel applications.
Thus, it would be an improvement in the art to provide less expensive, more efficient electrolytic methods of producing alkali alkoxides from alkali metal salt solutions using an alkali ion conducting ceramic solid electrolyte or ceramic membrane. It would further be an advancement in the art to provide such a method of making alkali alkoxides that is simple, safe, and environmentally benign. Such a method is provided herein.